Poster Presentation

Dr. Yan-e Zhao, SJTU, China

In-wheel-motor drive electric vehicle (EV) is an innovative configuration, in which each wheel is driven individually by an electric motor. Such an EV has many mechanical and electrical advantages. It permits more space by eliminating the central drive motor, the transmission, the heavy mechanical differential and the drive shaft, etc. Moreover, the independent wheel drive structure makes it possible to control each wheel torque independently, which improves vehicle handling and stability distinctly during steering or driving along straight lines on slippery roads. Independent driven wheels provides torque steering as another steering input and the vehicle yaw rate can be controlled by the direct yaw-moment generated from the driving and braking forces. Nevertheless, the whole vehicle system is complex and nonlinear considering the characters of the tire and the steering angle as well as the load shift during curving. Accordingly, the control system of such an EV becomes more complicated. To address this problem, a new Direct Yaw-moment Control (DYC) system is proposed to improve the handling and stability of a four-independent-wheel drive electric vehicle. The control system is based on a fuzzy logic direct yaw-moment controller together with fuzzy slip controllers for each wheel. By measurements of vehicle states, the control algorithm determines the level of vehicle stability and intervenes as necessary through individual wheel traction control to provide added stability and handing predictability. Therefore, the DYC system distributes torque and power to each motor to meet the requirements of each wheel. The effectiveness and validation of the proposed control method are evaluated in a Matlab/Simulink environment. In addition, experimental validation is conducted for verifying the accuracy and the effectiveness of proposed yaw-rate control algorithm. The simulation and experiment results manifest that the DYC system can assist the driver with controlling the stability of the vehicle during adverse driving maneuvers over a variety of road conditions. The new DYC system can maintain the vehicle stability and enhance the performances of the EV vehicle significantly.

Poster presentation: Future powertrain solutions